Process of preparing dialkyl-barbituric acid.



UNIT D STATES Patented November 24, 1903; V

PATENT OFFICE.- 1'

MAX ENGELMANN, OF ELBERFELD, GERMANY, AssIeNoR TO FARBnNnA-x BRIKEN OFELBERFELD 00., OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

PROCESS OF PREPARING DIA LKYL-BAR BlTURlC ACID.

SPECIFICATION forming part of Letters Patent No. 744,732, dated November24, 1908.

Application filed September 2,1903. Serial No. 171,700. (No specimens.)

NH-OO I5 I R oo o l R NHCO (R meaning an alkyl radical) which bodiespossess valuable therapeutic, especially sopo-' rific, properties.

The process for the preparation of these compounds consists in firstcondensing urea and dialkyl cyano-acetic esters of the general formulaCN-C-OOOR by means of alkali alcoholates, and, secondly, splitting 0dammonia from the resulting dialkylated imino dioxypyrimidins of thegeneral formula by treatment with saponifying agents.

In order to carry out my process practically, I can, for instance,proceed as follows: Fourteen parts of sodium are dissolved in fivehundred parts of alcohol and the solution thus obtained is mixed withone hundred parts of the'ethylic ester of diethyl cy ano acetic acid andwith forty parts of urea. It is heated for six hours on the water-bath,the alcohol is distilled off, and the residual sodium salt of thediethyl imino dioxypyrimidin is decomposed by means of dilute aceticacid. By a recrystallization from hot water the free body is obtained inthe shape of crystals melting at 285. centigrade. Ten parts of the5-diethyl-4t-imino-2-6-dioxypyrimidin thus obtained are heated on thewater-bath for abouthalf an hour with thirty parts of a fifteen-percent.sulfuric acid. The body enters into solution and after some time thediethyl barbituric acid deposits in'the shape of needles.. It isfiltered ofi, recrystallized from water, and dried. The saponificationcan also be carried out with other saponifying agents, such ascaustic-soda lye or the like. The process proceeds in an analogousmanner for the production of the other dialkyl-barbituric acids.

Having now described my invention and in what manner the same is to beperformed, what I claim as new, and desire to secure by Letters Patent,is

1. The process for the production of dialkyl-barbituric acids having theabove-given general formula, which process consists in first condensingurea and dialkyl cyano acetic esters by means of alcoholates of alkaliesand secondly splitting ofi ammonia from the resultingo-dialkylt-imino-2-6-dioxypyrimidin by treatment with saponifyingagents, substantially as hereinbefore described.

2. The process for the production of diethyl-barbituric acid, whichprocess consists in first condensing urea and diethyl-cyano acetic esterby means of alcoholates of alkalies and secondly splitting ofi ammoniafrom the resulting 5-diethyl-4dmino-2-6-dioxypyrimidin by treatment withsaponifying agents, substantially as hereinbefore described.

3. The process for the production of diethyl-barbituric acid, whichprocess consists in first condensing urea and the ethylic ester 01":diethyl-cyano-acetic acid by means of soname in the presence of twosubscribing witdium ethylate and secondly splitting off amnesses. moniafrom the resulting 5-diethyL4-imino- Z-G-dioxypyrimidin by treatmentwith hot MAX ENGELMANN' 5 sulfuric acid, substantially as hereinbeforeWitnesses:

described. OTTO K6NIG,

In testimony whereof I have signed my 1 F. A. RITTERSHAUS.

